Some vehicles incorporate a fully automatic transmission in which gear selections are performed without user input. For this purpose, a transmission controller is provided which determines when gear changes should be made and then implements automatic upshifts and downshifts accordingly. Typically, gear changes are made automatically in accordance with a set of control regimes which correspond to user-selectable modes of operation. For example, there may be a “normal” or “drive” mode, in which gear upshifts are effected at relatively low engine speeds so as to provide efficient operation, and a “sport” mode, in which upshifts are effected at higher engine speeds for enhanced acceleration. More advanced vehicles may include several further modes of operation relating to a range of different driving conditions that the vehicle may encounter.
Many electronically controlled transmissions offer the option for a driver to manually request a gear change by operating an input device. The input device generates a request signal for an upshift or a downshift which is sent to the transmission controller, which implements the requested gear change within prescribed limits. For example, a request to downshift will not be implemented if the projected engine speed is too high in the proposed target gear, and an automatic downshift may be implemented to avoid an engine stall, but otherwise the transmission is held in the gear selected by the driver.
One known example of an input device for manual gearshift control is a paddle gearshift selector system, in which two paddle-shaped levers are provided on diametrically-opposite sides of a steering wheel. Each lever acts as an input device, and is operable to close a microswitch to trigger a gear change event. The levers are typically positioned behind the steering wheel in such a way that enables a driver of the vehicle to operate the levers with their fingers whilst simultaneously gripping the steering wheel, allowing the driver to select gears without taking a hand off the steering wheel.
The gearshift selector system forms part of a steering assembly which includes a steering column housing and the steering wheel, along with various other controls such as indicator stalks and cruise control activators. In these arrangements, the levers are either mounted directly to the steering wheel, or to the steering wheel column housing immediately behind the steering wheel. Typically, one lever is operable to shift up a gear, and the other lever is operable to shift down a gear, and the appropriate lever is pulled towards the driver to request the shift. In another arrangement, either one of the levers can be pulled towards the driver to change up a gear or pushed away from the driver to change down a gear.
In one type of system, when a lever is operated, the transmission switches into a temporary manual-selection mode, in which normal automatic gear changes are suspended and control of the gear selection passes to the driver. Automatic control may be resumed after a pre-determined period if no further manual gear change inputs are made by the driver.
One drawback to paddle gearshift selector systems is that, because of the intentional close proximity of the paddles to the steering wheel, the driver's hands can inadvertently trigger a gearshift, or accidentally set the transmission into the manual gear selection mode, whilst performing steering operations. This is particularly the case for operations in which the steering wheel needs to be manipulated rapidly, for example when undertaking complex maneuvers such as parking. In addition, if the steering wheel is turned by around 90° it is possible for the paddles to foul the driver's legs or clothing, which could also trigger an unintentional gearshift or an unexpected switch into manual gear selection mode.
Against this background, it would be desirable to provide an improved input device for a gearshift system for use in a vehicle, which overcomes or at least substantially alleviates the disadvantages known in the prior art.